Services

Sample Preperation:

All samples should be solids or pressed powders capable of withstanding pressure gradients from atmosphere to ~10-10 Torr. If the sample is a powder it will be pressed onto conductive carbon tape just prior to analysis by this laboratory. Solid samples should be round or square with a ~9 mm diameter or hypotenuse respectively and a thickness of no more than 2 mm, and these should be prepared by the customer. The customer should submit a detailed account of the probable components and an MSDS of the material.

Samples should not overly out-gas. Gentle heating of the sample may be necessary for degassing. If a base pressure of ~10-8 Torr cannot be established after 2 hr. of turbo-molecular pumping with mild heating, then the sample is not amenable to ESCA. In such a case, sample analysis charges will still apply.

ESCA Services:

This service will provide identification of chemical constituents in solid materials or supported thin films.The investigation will utilize K-α x-rays from either a magnesium or aluminum anode. The anode choice will be determined by the operator after considering the positions of the Auger structures of the various sample constituents.A full investigation will be conducted with one anode, unless otherwise arranged with the customer.

The analysis will also provide an estimate of atomic percent composition of the sample surface.The concentration of species in mixed materials must be at least 0.05 % for accurate determination, and concentration analysis will focus on major constituents.

The final report will contain a labeled XPS survey of the material with elemental identification.Additional higher resolution windows will be taken for the major species to attempt to extract oxidation state information.Typical resolution for these experiments are 0.9 - 1.4 eV FWHM for an ideal homogeneous one or two component system.

Approximate time for doing ESCA service for one sample: 1 day

AES Services:

The primary function of AES is the identification of the lighter elements [Beryllium through Krypton], but all elements heavier than Helium do produce Auger electrons and can be investigated. The technique can help to discriminate between two species which are hard to distinguish in XPS (for example Pt and Pd), and AES is an excellent supplement to XPS for accurate elemental identification. For ideal surfaces, the fine structure AES analysis can yield valence state information for a particular element.

This service will provide chemical identification of the lighter elements in a material, especially the surface contaminants. It will also attempt to quantify the relative ratios of surface species, but this is not always possible with heterogeneous materials. The technique of AES can also examine the components in segregated regions on a surface, but those regions must be visible to the naked eye. For accurate AES analysis, the sample surface should be conductive. The final report will contain a labeled AES survey in differential form.

Approximate time for facility time for one sample: 1 day